'99 GL1500SE. 144,000 miles - runs like a top. I've had an oil leak for a while and now I'm trying to find its source. Oil is quite wet on the coolant drain plug and the water pump cover is oiliest on the clutch side of the bike. There's oil on the crankcase but it's dry, oil down the side of the engine on the clutch side - drier the farther back it goes. Hard to see but I'm reasonably sure it's not a head gasket leak. I'm thinking it's the o-ring on the water pump. Seems like o-rings don't fail often though. I'm wondering if I'm getting too much crankcase pressure but don't know how to check it. Any experience here appreciated. Please hold guesses - got plenty of those.